I have never had this problem till just 2 weeks ago. I finally had to turn on the A/C on my stocker 97 Z. When i am at stop lights the voltage goes from about 14.5 on display down to a little less than 13. Not in the red but darn close! When this happens it feels like it could die but just runs rough. There is something that runs in the A/C that turns on for 10 seconds and then Turns off for 10 seconds, Then back on??? When it activates (every 20 seconds) that is what drops the Volts down. Is that the compressor drawing power off the alternator?

Has anyone else had this problem? New Alternator? I put in a new battery last month, and it runs fine normally.

 

well the on/off/on/off you speak of sounds like you are low on freon. i would check your freon pressure first and fill it if it is needed. then see if it is still dropping your volts with the a/c on.


what are the volts when the a/c is off? and yes you are drawing off your alternator

 

When it starts and is cold its up around 15 and settles around 14.5. The gauge has always been past the 13.5 Volts mark.

I forgot to add the metal part of the top hose that goes into the A/C compressor sweats alot and I can hear bubbling after the car is turned off. I have noticed it twice after a 35 minute drive last week. and the clear peep hole section appears to be empty inside on the pipes right there. Should it be filled with freon? but Car blows freezing cold air, no complaints there.

 

maybe you have a pressure switch on your a/c going?

 

I can actually hear the Belt very lightly pull like its under load at idel when the (20 second) A/C function starts running? It has to be the compressor connected to drive belt. Could it be bad a bad pully inside the Compressor? or would that be because its an alternator issue? I dont hear "squeaks" when the A/C is off?

 

well i thought whenever the ac was on, the fan automatically kicked on...

in any case, my ac does it and i believe the compressor is bad, I just don't use the AC ever. still blows cold air, but my car will overheat unless i'm driving on the highway without stop lights if my ac is on.

 

Could be the clutch in the compressor is on it's way out and causing serious drag on the belt bogging down the motor? I've had this happen before.

 

Had this same issue again today but found something else.... I used to think it was an A/C compressor issue but it must be electrical. Today i started dropping volts when sitting at idle at stoplights and then I just decided to sit in neutral and rev the engine. The exact second I took it out of "D" and put it in "N" the volts jumped immediatly back to 13... i never even touched the gas ??? So i tested it out someone and it worked everytime. Does anyone know what and how to repair this?

 

Have the same problem with my a/c, except it does't blow cold. I get the drop in voltage just as you described. Comes back up when I put it in neutral. Did you ever find out how to fix this? I don't know where to start, hoping it's not my compressor. It was replaced less than 2 years ago.

 

It turns out to be the 2nd radiator fan cycling on / off at stop lights while in gear. I cleaned (wire brushing and polishing) all my electrical connections around the battery and threw on a cheap alternator (AutoZone special). Now it does not drop volts like before but still takes a small hit when the fan activates. I should have approached it differently but it takes a second person to diagnose.

When in gear and idling, maybe the MAF sensor? is causing the RPM's not to change when more power is needed (A/C on, brakes on, ect). When in neutral or park the car is fine and knows to increase the RPM's??? Cleaning and changing the electrical components is working for now and has been since mid June.

But the problem will be back.